Calicotome Spinosa (Fabaceae) – Animal and Plant Health Spiny-Broom

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United States Department of Weed Risk Assessment Agriculture for Calicotome spinosa (Fabaceae) – Animal and Plant Health Spiny-broom

Inspection Service

March 4, 2021

Version 1

Calicotome spinosa in Sardinia (Hillewaert, 2008)

AGENCY CONTACT Plant Epidemiology and Risk Analysis Laboratory (PERAL) Science and Technology

Plant Protection and Quarantine (PPQ) Animal and Plant Health Inspection Service (APHIS) United States Department of Agriculture (USDA) 1730 Varsity Drive, Suite 300 Raleigh, NC 2760 Weed Risk Assessment for Calicotome spinosa (Spiny-broom)

Executive Summary

The result of the weed risk assessment for Calicotome spinosa is High Risk of becoming weedy or invasive in the United States. Calicotome spinosa is a perennial nitrogen-fixing shrub in the family Fabaceae that can be a weed of natural areas and pastures. It was detected in California in 2016, but the plants were removed. It has been proposed for an “A” list pest rating in that state, but it has not been regulated yet. No other states regulate the species, but Idaho regulates the genus Cytisus, in which Calicotome spinosa was previously placed. It is not known to be present in the United States. Plants form dense patches and resprout from fire and clear cutting. Because they are highly flammable, they can also increase the risk of fire. The seeds can be dispersed on clothing, in garden waste, and on earth-moving machinery. Calicotome spinosa is an environmentally significant weed and a weed of agriculture in Australia, where it is managed with mechanical and chemical controls. It is also managed in New Zealand and regulated in both countries. The plant can prevent livestock from accessing water and reduce the productivity of pastures. It also prevents the growth of native species and is considered a serious threat to the native vegetation of Victoria, Australia. It is most likely to enter the United States on machinery or as a contaminant of seed or grain. We estimate that 6 to 20 percent of the United States is climatically suitable for the species to establish.

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Plant Information and Background

PLANT SPECIES: Calicotome spinosa (L.) Link (Fabaceae) (NPGS, 2020)

SYNONYMS: Basionym: Spartinum spinosum L. Other synonyms: Cytisus spinosus (L.) Lam., Calicotome fontanesii Rothm., Calycotome spinosa Link. (Biosecurity Queensland, 2016; NPGS, 2020; The Plant List, 2013b)

COMMON NAMES: Spiny-broom (NPGS, 2020), thorny broom (Salmi et al., 2018)

BOTANICAL DESCRIPTION: Calicotome spinosa is a spiny shrub with many branches that grows up to 3 meters tall. The leaves are dark green to grayish green, the flowers are bright yellow, and the spines can be up to 7.5 cm long. The seed pods are 2.5 to 4 cm long and gray, black, or reddish brown with two ridges on one edge. Seeds are smooth, shiny, and yellowish brown, about 3.5 mm long and 2 mm wide (Biosecurity Queensland, 2016; Parsons and Cuthbertson, 2001; Salmi et al., 2018).

INITIATION: Due to potential concern about this species becoming invasive in the United States, the PPQ Weeds Cross-Functional Working Group requested that this species be evaluated with a weed characterization. Upon review, the characterization triggered the need for a more thorough weed risk assessment.

WRA AREA1: United States and Territories.

FOREIGN DISTRIBUTION: Calicotome spinosa is native to Algeria, Libya, Italy, France, and Spain (NPGS, 2020). It is naturalized in New Zealand and Australia (Victoria) (Biosecurity Queensland, 2016; Groves et al., 2005; Howell and Sawyer, 2006; NPGS, 2020). It was introduced to Australia in the 1860s as an ornamental and a hedge plant (Paynter et al., 2003a) and has escaped from cultivation (Randall, 2007). It is regulated in Victoria and Western Australia (Biosecurity Queensland, 2016; Groves et al., 2005}). In New Zealand, it is regulated and listed as a harmful organism (MAF Biosecurity New Zealand, 2012; PCIT, 2020)

U.S. DISTRIBUTION AND STATUS: Calicotome spinosa was detected in California in 2016 (Oki, 2016); the population was removed, though the seed bank has not been evaluated (Kelch, 2020). It is not known to be present anywhere else in the United States (EDDMaps, 2020; Kartesz, 2015; NRCS, 2020). The website Dave’s Garden (2020) describes the plant as drought-tolerant and suitable for xeriscaping, but users on the forums have made no comments on the species. Garden Web (2020) has no discussions on the plant. We did not find it offered for sale online (Amazon, 2020; Plant Information Online, 2020). In California, it is proposed for an “A” list pest rating, but regulations are not yet in place (Kelch, 2020). Idaho regulates the genus Cytisus (ISDA, 2018),

1 The “WRA area” is the area in relation to which the weed risk assessment is conducted (definition modified from that for “PRA area”) (IPPC, 2017).

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which previously included Calicotome (Cristofolini and Troia, 2006). The species is not otherwise regulated in the United States (NPB, 2021).

Analysis

ESTABLISHMENT/SPREAD POTENTIAL: Calicotome spinosa fixes nitrogen, using bacteria in the genus Bradyrhizobium (Cardinale et al., 2008; Salmi et al., 2018). It resprouts after fire and clear- cutting (Casal, 1987; Paula and Pausas, 2006), and soil disturbance and fire induce seeds in the soil to germinate (Weeds Australia, 2011). Long-term control requires exhausting the seed bank and eliminating new plants before they flower (Weeds Australia, 2011). Its dense growth and spiny branches make it an effective hedge (Parsons and Cuthbertson, 2001); it has formed dense patches in natural areas (Biosecurity Queensland, 2016). Earth-moving machinery can disperse it in soil; it can also move on clothing and in discarded garden waste (Biosecurity Queensland, 2016; Parsons and Cuthbertson, 2001). It is naturalized in Australia and New Zealand (Biosecurity Queensland, 2016; NPGS, 2020), and the seeds can be contaminants of agricultural products (Agriculture Victoria, 2020; Biosecurity Queensland, 2016), but we found no records of interception at U.S. ports of entry (AQAS, 2020). We had high uncertainty for this risk element, largely because it is not clear whether the species is actually spreading.

Risk score = 9.0 Uncertainty index = 0.26

IMPACT POTENTIAL: Calicotome spinosa is an environmental and agricultural weed in Australia (Biosecurity Queensland, 2016; Groves et al., 2005; Randall, 2007). Because it fixes nitrogen, it can change soil nutrient levels (Biosecurity Queensland, 2016). It is also highly flammable, and dense patches can increase the risk of fire (Biosecurity Queensland, 2016; Dehange et al., 2017). It is rated as a serious threat to native vegetation in Victoria (Weeds Australia, 2011). Groves et al. (2005) consider it to be an environmentally significant weed that warrants control in Australia, and it is also managed in Canterbury, New Zealand (Williams and Braithwaite, 2003). In agricultural systems, the weed can prevent livestock from accessing water and reduce the productivity of pastures (Biosecurity Queensland, 2016; Parsons and Cuthbertson, 2001). Livestock will eat young shoots but avoid mature plants because of the spines (Parsons and Cuthbertson, 2001). It is listed as a noxious weed in Australia (Randall, 2007) and as a harmful organism in New Zealand (PCIT, 2020). Parsons and Cuthbertson (2001) provide recommendations for mechanical and chemical control. We had low uncertainty for this risk element because the species has relatively few types of impact, but these are well documented.

Risk score = 3.5 Uncertainty index = 0.07

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RISK MODEL RESULTS: The risk scores for establishment/spread and impact potential were used to estimate the probabilities of invasiveness and overall risk result (Figure 1).

Model Probabilities: P(Major Invader) = 52.3% P(Minor Invader) = 45.0% P(Non-Invader) = 2.7% Risk Result = High Risk Risk Result after Secondary Screening = Not Applicable

Figure 1. Risk and uncertainty results for Calicotome spinosa. The risk score for this species (solid black symbol) is plotted relative to the risk scores of the species used to develop and validate the PPQ WRA model (Koop et al., 2012). The results from the uncertainty analysis are plotted around the risk score for C. spinosa. The smallest, black box contains 50 percent of the simulated risk scores, the second 95 percent, and the largest 99 percent. The black vertical and horizontal lines in the middle of the boxes represent the medians of the simulated risk scores (N=5000). For additional information on the uncertainty analysis used, see Caton et al. (2018)

GEOGRAPHIC POTENTIAL: Using the PPQ climate-matching model for weeds (Magarey et al., 2017), we estimate that about 6 to 20 percent of the United States is suitable for the establishment of C. spinosa (Fig. 2). The smaller number is the percentage for which we have a very high certainty of climate suitability, while the larger percentage includes areas for which we have a lower certainty of climate suitability. The larger area represents the joint distribution of Plant Hardiness Zones 7-11,

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areas with 0-50 inches of annual precipitation, and the following Köppen-Geiger climate classes: steppe, Mediterranean, humid subtropical, and marine west coast (See Appendix). The area of the United States shown to be climatically suitable was determined using only these three climatic variables. Other factors, such as soil, hydrology, disturbance regime, and species interactions may alter the areas in which this species is likely to establish. Calicotome spinosa grows on sunny, rocky slopes (Salmi et al., 2018); in woodlands, grasslands, pastures, and disturbed areas; and on roadsides (Agriculture Victoria, 2020; Biosecurity Queensland, 2016). The records in the Global Biodiversity Information Facility (GBIF Secretariat, 2019) indicate that it is largely a coastal species. It is a major component of degraded, overgrazed scrubland in Algeria (Kouider et al., 2014). Although it is typically found in dry, rocky places with well-drained soil (PFAF, 2020), it has escaped cultivation in wet temperate areas of Australia (Biosecurity Queensland, 2016) and is present on weedy roadsides and adjacent farms (Weeds Australia, 2011). It is reported to grow best in PHZ 7-11 (Dave's Garden, 2020; PFAF, 2020), but it can tolerate temperatures down to -10 °C if the soil drainage is ideal (PFAF, 2020).

ENTRY POTENTIAL: Seeds of Calicotome spinosa can be dispersed on machinery (Biosecurity Queensland, 2016) and as contaminants of agricultural products, including animal feed (Agriculture Victoria, 2020; Biosecurity Queensland, 2016). In New Zealand, the species is regulated in seed for sowing and of grain and seed for consumption (MAF Biosecurity New Zealand, 2009, 2012). We found no records, however, of interceptions at U.S. ports of entry (AQAS, 2020). The risk score for this risk element can range from 0 to 1, where 0 indicates that there is no evidence of any pathways for entry into the United States.

Risk score = 0.12 Uncertainty index = 0.26

Discussion

The result of the weed risk assessment for Calicotome spinosa is High Risk of becoming weedy or invasive in the United States. Although C. spinosa is naturalized in Australia and New Zealand (Groves et al., 2005; Howell and Sawyer, 2006), we did not find information indicating that it has spread beyond the initial regions of entry. If we did find evidence of spread, that would increase the risk score. Calicotome spinosa produces 3 to 15 seeds per pod (Parsons and Cuthbertson, 2001), but we did not find information on the number of pods produced. The risk score could increase or decrease with that information, depending on whether the plant is a prolific seed producer. Although we found evidence for environmental impact, the information is relatively sparse; therefore, we are unsure of whether threatened or endangered species in the United States would be at risk. The species can overshadow understory plants (Biosecurity Queensland, 2016), but we found no evidence that it actually eliminates vegetation layers, which would increase the risk score.

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Figure 2. Potential distribution of Calicotome spinosa in the United States. Climatic suitability was determined using the APHIS-PPQ climate matching tool for invasive plants (Magarey et al., 2017).

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Suggested Citation

PPQ. 2020. Weed risk assessment for Calicotome spinosa (L.) Link (Fabaceae) – Spiny-broom. United States Department of Agriculture, Animal and Plant Health Inspection Service, Plant Protection and Quarantine (PPQ), Raleigh, NC. 20 pp.

Literature Cited

Agriculture Victoria. 2020. Invasiveness Assessment - Spiny broom (Calicotome spinosa) in Victoria. Victorian Resources Online. http://vro.agriculture.vic.gov.au/dpi/vro/vrosite.nsf/pages/invasive_spiny_broom. Agriculture Victoria. 2021. Spiny broom. Department of Jobs, Precincts and Regions. https://agriculture.vic.gov.au/biosecurity/weeds/priority-weeds/spiny-broom. Amazon. 2020. Search for Calicotome spinosa. Amazon.com. Last accessed 8/19/2020, AQAS. 2020. Pest ID. Agricultural Quarantine Activity Systems. https://aqas.aphis.usda.gov/pestid/F309AdHocReportSubmit.do#defaultAnchor. Arroyo, J., A. Aparicio, R. G. Albaladejo, J. Munoz, and R. Braza. 2008. Genetic structure and population differentiation of the Mediterranean pioneer spiny broom Calicotome villosa across the Strait of Gibraltar. Biological Journal of the Linnean Society 93:39-51. Baghdadi, D., M. Faafaa, A. Benardj, D. Anteur, and A. Hartani. 2019. Contribution to the phytodiversity study of the Ouled Sidi Abdelaziz (forest of Ouled Sidi Yahia) in north-west of Algeria. Biodiversity Journal 10(3):259-264. Biosecurity Queensland. 2016. Weeds of Australia. Queensland Government. https://keyserver.lucidcentral.org/weeds/data/media/Html/calicotome_spinosa.htm. CABI. 2020. Crop Protection Compendium. CAB International. https://www.cabi.org/cpc/datasheet/10814. Cardinale, M., A. Lanza, M. L. Bonni, S. Marsala, A. M. Puglia, and P. Quatrini. 2008. Diversity of rhizobia nodulating wild shrubs of Sicily and some neighboring islands. Archives of Microbiology 190:461-470. Casal, M. 1987. Post-fire dynamics of shrubland dominated by Papilionaceae plants. Ecologia Mediterranea 13(4):87-98. Caton, B. P., A. L. Koop, L. Fowler, L. Newton, and L. Kohl. 2018. Quantitative uncertainty analysis for a weed risk assessment model. Risk Analysis 38(9):1972-1987. Cristofolini, G., and A. Troia. 2006. A reassessment of the sections of the genus Cytisus Desf. (Cytiseae, Leguminosae). Taxon 55(3):733-746. Dave's Garden. 2020. Calicotome Species, Thorny Broom, Spiny Broom. Internet Brands. https://davesgarden.com/guides/pf/go/198092/#b. Dehange, B., C. Hernando, M. Guijarro, and J. Madrigal. 2017. Flammability of some companion species in cork oak (Quercus suber L.) forests. Annals of Forest Science doi:10.1007/s13595- 13017-10659-13595. EDDMaps. 2020. Early Detection and Distribution Monitoring System. University of Georgia, Center for Invasive Species and Ecosystem Health. https://www.eddmaps.org/distribution/. GardenWeb. 2020. GardenWeb Forums. Houzz Inc. https://www.gardenweb.com/.

Ver. 1 March 4, 2021 7 Weed Risk Assessment for Calicotome spinosa (Spiny-broom)

GBIF Secretariat. 2019. GBIF Backbone Taxonomy. Global Biodiversity Information Facility. https://www.gbif.org/species/2956359. Groves, R. H., R. Boden, and W. M. Lonsdale. 2005. Jumping the Garden Fence: Invasive garden plants in Australia and their environmental and agricultural impacts. World Wide Fund for Nature - Australia, Ultimo, Australia. 173 pp. Gulias, J., A. Mairata, J. Frontera, I. Janer, J. Jaume, and J. Cifre. 2016. Firebreak maintenance with equines in Serra de Tramuntana mountains (Mallorca, UNESCO world heritage). Pages 333- 336 in I. Casasus and G. Lombardi, (eds.). Mountain pastures and livestock farming facing uncertainty: environmental, technical and socio-economic challenges. Centre International de Hautes Etudes Agronomiques Mediterraneennes, Zaragoza, Spain. Heap, I. 2020. International Herbicide-Resistant Weed Database. www.weedscience.org. Heide-Jorgensen, H. S. 2008. Parasitic Flowering Plants. Brill, Leiden, the Netherlands. Hillewaert, H. 2008. File: Calicotome spinosa (habitus).jpg. Wikimedia Commons. https://commons.wikimedia.org/wiki/File:Calicotome_spinosa_(habitus).jpg. Howell, C., and J. W. D. Sawyer. 2006. New Zealand Naturalized Vascular Plant Checklist. New Zealand Plant Conservation Network, Wellington, New Zealand. 60 pp. IPPC. 2017. International Standards for Phytosanitary Measures No. 5: Glossary of Phytosanitary Terms. Food and Agriculture Organization of the United Nations, Secretariat of the International Plant Protection Convention (IPPC), Rome, Italy. 34 pp. ISDA. 2018. Summaries of External Quarantines. Idaho State Department of Agriculture, Boise, ID. 22 pp. Kartesz, J. T. 2015. Taxonomic Data Center. Biota of North America Program. http://bonap.net/tdc. Kelch, D. G. 2020. Re: status of Calicotome spinosa in California? Personal communication to K. A. Israel on August 19, 2020, from D.G. Kelch (CDFA/PHPPS Permits and Regulation/Environmental Compliance/PDAS). Koop, A., L. Fowler, L. Newton, and B. Caton. 2012. Development and validation of a weed screening tool for the United States. Biological Invasions 14(2):273-294. Kouider, C., Z. Mehdadi, A. Latreche, Z. Hazem, and W. El Zerey. 2014. Impact of livestock grazing on the floristic composition: a case study of the Mount of Tessala, western Algeria. International Journal of Environment 3(3):186-200. Mabberley, D. J. 2008. Mabberley's Plant-Book. Cambridge University Press, Cambridge, UK. 1021 pp. MAF Biosecurity New Zealand. 2009. Import Health Standard BNZ.GCFP.PHR: Importation of Grains/Seeds for Consumption, Feed or Processing, Plant Health Requirements. Ministry of Agriculture and Forestry, Biosecurity New Zealand, Wellington, New Zealand. 191 pp. MAF Biosecurity New Zealand. 2012. Importation of Seed for Sowing (Standard 155.02.05). Ministry of Agriculture and Forestry, Biosecurity New Zealand, Wellington, New Zealand. 156 pp. Magarey, R., L. Newton, S. C. Hong, Y. Takeuchi, D. Christie, C. S. Jarnevich, L. Kohl, M. Damus, S. I. Higgins, L. Millar, K. Castro, A. West, J. Hastings, G. Cook, J. Kartesz, and A. L. Koop. (journal article). 2017. Comparison of four modeling tools for the prediction of potential distribution for non-indigenous weeds in the United States. Biological Invasions 20(3):679–694. Mazurek, H., and F. Romane. 1986. Dynamics of young Pinus pinaster vegetation in a Mediterranean area: diversity and niche-strategy. Vegetatio 66:27-40. Mebirouk-Boudechiche, L., L. Boudechiche, M. Chemman, S. Djaballah, I. Bouzouraa, and C. Cherif. 2015. Une estimation de la biomasse foliare fourragere de Pistacia lentiscus et Calycotome spinosa, arbustes des suberaies en Algerie. Fourrages 221:77-83.

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NPB. 2021. Laws and Regulations. National Plant Board. https://nationalplantboard.org/laws-and- regulations/. NPGS. 2020. Germplasm Resources Information Network (GRIN - Taxonomy). United States Department of Agriculture, Agricultural Research Service, National Plant Germplasm System. https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=8670. NRCS. 2020. The PLANTS Database. United States Department of Agriculture, Natural Resources Conservation Service. https://plants.sc.egov.usda.gov/java/. Oki, L. 2016. CDFA nursery advisory board report Spring 2016. University of California, Division of Agriculture and Natural Resources, Davis, CA. Last accessed 8/18/2020, http://ucnfanews.ucanr.edu/Articles/Gleanings_from_Meetings/CDFA_nursery_advisory_board_ report/. Parker, I. M. 1997. Pollinator limitation of Cytisus scoparius (Scotch broom), an invasive exotic shrub. Ecology 78(5):1457-1470. Parsons, W. T., and E. G. Cuthbertson. 2001. Noxious Weeds of Australia. CSIRO Publishing, Collingwood, Australia. 698 pp. Paula, S., and J. G. Pausas. 2006. Leaf traits and resprouting ability in the Mediterranean basin. Functional Ecology 20:941-947. Paynter, Q., S. M. Csurhes, T. A. Heard, J. Ireson, M. H. Julien, J. Lloyd, W. M. Lonsdale, W. A. Palmer, A. W. Sheppard, and R. D. van Klinken. 2003a. Worth the risk? Introduction of legumes can cause more harm than good: an Australian perspective. Australian Systematic Botany 16:81-88. Paynter, Q., P. O. Downey, and A. W. Sheppard. 2003b. Age structure and growth of the woody legume weed Cytisus scoparius in native and exotic habitats: implications for control. Journal of Applied Ecology 40:470-480. PCIT. 2020. Phytosanitary Export Database. United States Department of Agriculture, Phytosanitary Certificate Issuance & Tracking System. https://pcit.aphis.usda.gov/PExD/faces/ReportFormat.jsp. PFAF. 2020. Calicotome spinosa - (L.) Link. Plants for a Future. https://pfaf.org/user/Plant.aspx?LatinName=Calicotome+spinosa. Plant Information Online. 2020. Plant Search. University of Minnesota. https://plantinfo.umn.edu/search/plants. Randall, R. P. 2007. The introduced flora of Australia and its weed status. Cooperative Research Centre for Australian Weed Management, Glen Osmond, Australia. 528 pp. Ricketts, T. H., E. Dinerstein, D. M. Olson, C. J. Loucks, W. Elchbaum, D. DellaSala, K. Kavanagh, P. Hedao, P. T. Hurley, K. M. Carney, R. Abell, and S. Walters. 1999. Terrestrial Ecoregions of North America: A Conservation Assessment. Island Press, Washington, DC. 485 pp. Rodriguez-Riano, T., A. Ortega-Olivencia, and J. A. Devesa. 1999. Reproductive biology in two Genisteae (Papilionideae) endemic of the western Mediterranean region: Cytisus striatus and Retama sphaerocarpa. Canadian Journal of Botany 77:809-820. Salmi, A., F. Boulila, Y. Bourebaba, C. Le Roux, D. Belhadi, and P. de Lajudie. 2018. Phylogenetic diversity of Bradyrhizobium strains nodulating Calicotome spinosa in the northeast of Algeria. Systematic and Applied Microbiology 41:452-459. Sheppard, A., M. Haines, and T. Thomann. 2006. Native-range research assists risk analysis for non- targets in weed biological control: the cautionary tale of the broom seed beetle. Australian Journal of Entomology 45:292-297. Simmonds, H., P. Holst, and C. Bourke. 2000. The palatability, and potential toxicity of Australian weeds to goats. Rural Industries Research and Development Corporation, Kingston, Australia. 156 pp.

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Syrett, P., S. V. Fowler, E. M. Coombs, J. R. Hosking, G. P. Markin, Q. E. Paynter, and A. W. Sheppard. 1999. The potential for biological control of Scotch broom (Cytisus scoparius) (Fabaceae) and related weedy species. Biocontrol News and Information 20(1):17-34. The Plant List. 2013a. Calicotome infesta (C. Presl) Guss. Kew Botanical Gardens, Missouri Botanical Garden. http://www.theplantlist.org/tpl1.1/record/ild-8329. The Plant List. 2013b. Calicotome spinosa (L.) Link. Kew Botanical Gardens, Missouri Botanical Garden. http://www.theplantlist.org/tpl1.1/record/ild-8334. USDA. 2020. National Invasive Species Information Center. United States Department of Agriculture. https://www.invasivespeciesinfo.gov/terrestrial/plants/scotch-broom. Weber, J., and F. D. Panetta. 2006. Weed risk assessment of the DEH Alert List and other non-native plant species. Fifteenth Australian Weeds Conference, Adelaide, Australia. September 24-28, 2006. Weeds Australia. 2011. Calicotome spinosa (L.) Link. Centre for Invasive Species Solutions. https://profiles.ala.org.au/opus/weeds-australia/profile/Calicotome%20spinosa. Williams, P. A., and H. Braithwaite. 2003. The future of weeds in Canterbury landscapes. Canterbury Botanical Society Journal 37:73-86. Wink, M. 2004. Evolution of Toxins and Anti-nutritional Factors in Plants with Special Emphasis on Leguminosae. Pages 1-25 in T. Acamovic, C. S. Stewart, and T. W. Pennycott, (eds.). Poisonous Plants and Related Toxins. CAB International, Wellington, UK.

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Appendix. Weed risk assessment for Calicotome spinosa (L.) Link (Fabaceae)

The following table includes the evidence and associated references used to evaluate the risk potential of this taxon. We also include the answer, uncertainty rating, and score for each question.

Question ID Answer - Score Notes (and references) Uncertainty ESTABLISHMENT/SPREAD POTENTIAL ES-1 [What is the taxon’s establishment e - high 2 Calicotome spinosa is native to Algeria, and spread status outside its native Libya, Italy, France, and Spain and is range? (a) Introduced elsewhere =>75 naturalized in New Zealand (Howell and years ago but not escaped; (b) Sawyer, 2006; NPGS, 2020) and Australia Introduced <75 years ago but not (Victoria) (Biosecurity Queensland, 2016; escaped; (c) Never moved beyond its Groves et al., 2005). Because we did not find native range; (d) Escaped/Casual; (e) information describing its spread or evidence Naturalized; (f) Invasive; (?) Unknown] of widespread naturalization, which suggests invasiveness (i.e., spread), we answered "e." Since we did find evidence of impact and spread into particular habitats (Biosecurity Queensland, 2016), we had high uncertainty, and we answered "f" for the uncertainty simulation. ES-2 (Is the species highly n - low 0 It was historically grown as an ornamental domesticated) and a hedge plant (Biosecurity Queensland, 2016; Paynter et al., 2003a), but we found no evidence of breeding for traits that would reduce its invasive potential.

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Question ID Answer - Score Notes (and references) Uncertainty ES-3 (Significant weedy congeners) y - high 1 Salmi et al. (2018) list four species in the genus Calicotome: Calicotome spinosa, Calicotome villosa, Calicotome intermedia, and Calicotome infesta. The Plant List (2013a) includes Calicotome infesta as an accepted species, though the National Plant Germplasm System (NPGS, 2020) lists Calicotome infesta subsp. intermedia as a synonym of Calicotome intermedia and does not otherwise list Calicotome spinosa. We found no evidence that any Calicotome species other than C. spinosa are weeds. The genus Calicotome has been segregated from Cytisus (Cristofolini and Troia, 2006). Cytisus, including Calicotome and Chamaecytisus, encompasses about 60 species (Mabberley, 2008). Cytisus scoparius is a weed of natural areas (USDA, 2020) and pastures (Paynter et al., 2003b). It is regulated to varying degrees in Hawaii, Maryland, Utah, Montana, Wisconsin, Washington, Idaho, and Oregon (NPB, 2021). Cytisus multiflorus is on the Department of Environment and Heritage Alert List as a potential threat to natural ecosystems in Australia (Weber and Panetta, 2006); it is invasive in New Zealand (Sheppard et al., 2006). Cytisus striatus is invasive in the United States (Syrett et al., 1999) and regulated in Oregon (NPB, 2021). We answered “yes” with high uncertainty since the weedy species are from a closely- related genus. ES-4 (Shade tolerant at some stage of n - low 0 It is not shade-tolerant (PFAF, 2020) but its life cycle) requires exposure to full sun (Dave's Garden, 2020). The species is only known from open habitats (Agriculture Victoria, 2020). ES-5 (Plant a vine or scrambling plant, n - negl 0 It is a shrub (Salmi et al., 2018), not a vine. or forms tightly appressed basal The leaves grow from the stems (Biosecurity rosettes) Queensland, 2016) and do not form a basal rosette. ES-6 (Forms dense thickets, patches, or y - low 2 It forms dense patches in invaded natural populations) areas (Biosecurity Queensland, 2016). The dense growth combined with spiny branches makes it an effective hedge (Parsons and Cuthbertson, 2001). ES-7 (Aquatic) n - negl 0 It is a shrub that grows in sunny, rocky areas (Salmi et al., 2018); it is not an aquatic plant. ES-8 (Grass) n - negl 0 It is in the Fabaceae family (NPGS, 2020) and is not a grass. ES-9 (Nitrogen-fixing woody plant) y - negl 1 Calicotome spinosa is a shrub that fixes nitrogen using bacteria in the genus

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Question ID Answer - Score Notes (and references) Uncertainty Bradyrhizobium (Cardinale et al., 2008; Salmi et al., 2018). ES-10 (Does it produce viable seeds or y - negl 1 It reproduces by seed (Agriculture Victoria, spores) 2020; Biosecurity Queensland, 2016). ES-11 (Self-compatible or apomictic) n - high -1 We did not find information specific to Calicotome spinosa. Arroyo et al. (2008) observed a high percentage of outcrossing in Calicotome villosa, which suggests partial self-incompatibility. Woody legumes are often self-incompatible (Arroyo et al., 2008). In its close relative, Cytisus scoparius, Parker (1997) observed four times more fruit production in cross-pollinated plants than in those that were self-pollinated, suggesting partial self-incompatibility. Rodriguez-Riano et al. (1999) observed very little fruit production in Cytisus striatus plants that were self-pollinated, and they note that Cytisus multiflorus and Cytisus grandiflorus are also self-incompatible. We answered "no" but had high uncertainty since our evidence is from congeners and close relatives. ES-12 (Requires specialist pollinators) n - mod 0 It is pollinated by insects (PFAF, 2020). We found no evidence of specialist pollinators, so we answered "no" with moderate uncertainty. ES-13 [What is the taxon’s minimum c - low 0 It is a perennial (Biosecurity Queensland, generation time? (a) less than a year 2016). Plants are unlikely to flower before with multiple generations per year; (b) 1 they are two to three years old (Parsons and year, usually annuals; (c) 2 or 3 years; Cuthbertson, 2001). We answered "c" with (d) more than 3 years; or (?) unknown] low uncertainty. Our alternate answers were "b" and "d." ES-14 (Prolific seed producer) ? - max 0 Unknown. Each fruit contains 3 to 15 seeds (Parsons and Cuthbertson, 2001), but we did not find information on fruit production or seed viability. ES-15 (Propagules likely to be dispersed y - low 1 Seeds can be dispersed on clothing, on unintentionally by people) machinery, in soil, and in discarded garden waste (Biosecurity Queensland, 2016; Parsons and Cuthbertson, 2001). They are spread in soil by earth-moving machinery (Parsons and Cuthbertson, 2001). ES-16 (Propagules likely to disperse in y - mod 2 Seeds can be contaminants of agricultural trade as contaminants or hitchhikers) products (Biosecurity Queensland, 2016), including animal feed (Agriculture Victoria, 2020). We found no records, however, of interception at U.S. ports of entry (AQAS, 2020). ES-17 (Number of natural dispersal 1 -2 Propagule traits for questions ES-17a vectors) through ES-17e. Fruits are pods 2.5 to 4 cm long; gray, black, or reddish brown in color

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Question ID Answer - Score Notes (and references) Uncertainty with two ridges on one edge. Seeds are smooth, shiny, and yellowish brown, 3.5 mm long and 2 mm wide (Parsons and Cuthbertson, 2001). ES-17a (Wind dispersal) n - low Heat causes the pods to burst open, ejecting seeds up to 1 m away (Parsons and Cuthbertson, 2001). Based on images, however, they do not have any adaptations to be dispersed by wind (Biosecurity Queensland, 2016). We found no evidence of wind dispersal. ES-17b (Water dispersal) ? - max Unknown. Biosecurity Queensland (2016) reports that seeds are water-dispersed, but we found no evidence of adaptation for water dispersal. ES-17c (Bird dispersal) n - low We found no evidence of dispersal by birds. Furthermore, the fruits do not appear to be fleshy and attractive to birds (Biosecurity Queensland, 2016). ES-17d (Animal external dispersal) n - high Unknown; the Weeds of Australia database (Biosecurity Queensland, 2016) indicates that the seeds can be dispersed by animals, but it does not provide details. The fruits and seeds, however, do not appear to have any adaptations that would allow them to stick to fur (Biosecurity Queensland, 2016). ES-17e (Animal internal dispersal) ? - max Unknown; the Weeds of Australia database (Biosecurity Queensland, 2016) indicates that the seeds can be dispersed by animals, but it does not provide details. ES-18 (Evidence that a persistent (>1yr) y - mod 1 Long-term control requires exhausting the propagule bank (seed bank) is formed) seed bank and eliminating new plants before they flower (Weeds Australia, 2011). ES-19 (Tolerates/benefits from y - negl 1 It resprouts after fire and clear-cutting (Casal, mutilation, cultivation or fire) 1987; Mazurek and Romane, 1986; Paula and Pausas, 2006). In Algeria, its presence indicates that fire has occurred (Baghdadi et al., 2019). Mechanical control requires removal of most of the root material because it can resprout (Weeds Australia, 2011), though the Plants for a Future database (PFAF, 2020) indicates that it does not tolerate root disturbance well. Plants that are damaged will resprout from the crown (Parsons and Cuthbertson, 2001). Although it is outside the scope of this question, it is important to note that fire and soil disturbance cause seeds in the soil to germinate (Weeds Australia, 2011). ES-20 (Is resistant to some herbicides or n - negl 0 Picloram and glyphosate are effective has the potential to become resistant) against it (Parsons and Cuthbertson, 2001).

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Question ID Answer - Score Notes (and references) Uncertainty It is not listed in the International Herbicide- Resistant Weed Database (Heap, 2020). ES-21 (Number of cold hardiness zones 6 0 suitable for its survival) ES-22 (Number of climate types suitable 6 2 for its survival) ES-23 (Number of precipitation bands 6 0 suitable for its survival)

IMPACT POTENTIAL General Impacts Imp-G1 (Allelopathic) n - low 0 It is not known to be allelopathic (Agriculture Victoria, 2020). Imp-G2 (Parasitic) n - negl 0 We found no evidence that C. spinosa is parasitic, and it is not a member of a family known to include parasitic species (Heide- Jorgensen, 2008). Impacts to Natural Systems Imp-N1 (Changes ecosystem processes y - negl 0.4 Because it fixes nitrogen, it can change soil and parameters that affect other nutrient levels (Biosecurity Queensland, species) 2016). It is highly flammable (Dehange et al., 2017), and the large biomass of dense patches can increase the risk of fire (Biosecurity Queensland, 2016; Oki, 2016). Imp-N2 (Changes habitat structure) n - mod 0 It can shade out understory plants (Biosecurity Queensland, 2016), but we found no evidence that it actually eliminates vegetation layers; therefore, we answered "no" with moderate uncertainty. Imp-N3 (Changes species diversity) y - low 0.2 It prevents the growth of native species (Biosecurity Queensland, 2016). It is rated as a serious threat to native vegetation in Victoria, Australia (Weeds Australia, 2011). Imp-N4 (Is it likely to affect federal y - high Although C. spinosa can have an Threatened and Endangered species?) environmental impact (Biosecurity Queensland, 2016; Oki, 2016), we found no evidence directly related to the United States. Therefore, we have high uncertainty. Imp-N5 (Is it likely to affect any globally n - mod 0 The area of the United States that is likely to outstanding ecoregions?) be suitable for C. spinosa includes globally significant ecoregions (Ricketts et al., 1999), but we do not have enough evidence to indicate that it would have widespread ecological impacts. Imp-N6 [What is the taxon’s weed status c - negl 0.6 In Australia, it is considered an in natural systems? (a) Taxon not a environmentally significant sleeper weed that weed; (b) taxon a weed but no evidence warrants control (Groves et al., 2005). of control; (c) taxon a weed and Randall (2007) lists it as a weed of the evidence of control efforts] natural environment in Australia. It is a significant environmental weed in Victoria,

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Question ID Answer - Score Notes (and references) Uncertainty Australia (Biosecurity Queensland, 2016). It is managed in Canterbury, New Zealand (Williams and Braithwaite, 2003). Our alternative answers for the uncertainty simulation were both "b." Impact to Anthropogenic Systems (e.g., cities, suburbs, roadways) Imp-A1 (Negatively impacts personal n - low 0 We found no evidence of this impact. property, human safety, or public infrastructure) Imp-A2 (Changes or limits recreational n - low 0 We found no evidence of this impact. use of an area) Imp-A3 (Affects desirable and n - low 0 We found no evidence of this impact. ornamental plants, and vegetation) Imp-A4 [What is the taxon’s weed status a - low 0 In the Port Phillip East region of Victoria, in anthropogenic systems? (a) Taxon Australia, landowners are required to control not a weed; (b) Taxon a weed but no the species and prevent it from spreading to evidence of control; (c) Taxon a weed adjacent roadsides (Biosecurity Queensland, and evidence of control efforts] 2016). This is not, however, evidence of control in anthropogenic systems as much as a regulation to control the spread of the weed into natural or production systems. We found no evidence that this species is specifically considered to be a weed in anthropogenic systems. Therefore, we answered "a" with low uncertainty. Our alternate answers were both "b." Impact to Production Systems (agriculture, nurseries, forest plantations, orchards, etc.) Imp-P1 (Reduces crop/product yield) y - low 0.4 It can prevent livestock from accessing water and reduce the productivity of pastures (Biosecurity Queensland, 2016; Parsons and Cuthbertson, 2001) Imp-P2 (Lowers commodity value) n - low 0 We found no evidence of this impact. Imp-P3 (Is it likely to impact trade?) y - low 0.2 It is listed as a noxious weed in Australia (Randall, 2007), is prohibited in Western Australia, and is regulated in Victoria (Biosecurity Queensland, 2016). It is also regulated in New Zealand (MAF Biosecurity New Zealand, 2012) and listed as a harmful organism there (PCIT, 2020). Because the seeds can be contaminants of agricultural products (Agriculture Victoria, 2020; Biosecurity Queensland, 2016), we answered “yes”. Imp-P4 (Reduces the quality or n - low 0 We found no evidence for this impact. availability of irrigation, or strongly competes with plants for water) Imp-P5 (Toxic to animals, including n - low 0 The young plants have been claimed to be livestock/range animals and poultry) toxic, but no evidence is available (Parsons and Cuthbertson, 2001). Several related

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Question ID Answer - Score Notes (and references) Uncertainty genera produce quinolizidine alkaloids, but Calicotome does not, possibly because it has spines for defense instead (Wink, 2004). Calicotome spinosa is palatable to goats and is not known to be toxic to them (Mebirouk- Boudechiche et al., 2015; Simmonds et al., 2000). Horses, donkeys, and mules eat the bark and young leaves (Gulias et al., 2016). Based on the preponderance of evidence, we answered "no" with low uncertainty. Imp-P6 [What is the taxon’s weed status c – mod 0.6 It is an agricultural weed in Australia in production systems? (a) Taxon not a (Randall, 2007). Parsons and Cuthbertson weed; (b) Taxon a weed but no evidence (2001) and Agriculture Victoria (Agriculture of control; (c) Taxon a weed and Victoria, 2021) provide recommendations for evidence of control efforts] mechanical and chemical control. Our answers for the uncertainty simulation were both "b." GEOGRAPHIC POTENTIAL Unless otherwise indicated, the following evidence represents geographically referenced points obtained from the Global Biodiversity Information Facility (GBIF Secretariat, 2019).

Plant hardiness zones Geo-Z1 (Zone 1) n – negl N/A We found no evidence of its presence in this zone. Geo-Z2 (Zone 2) n – negl N/A We found no evidence of its presence in this zone. Geo-Z3 (Zone 3) n – negl N/A We found no evidence of its presence in this zone. Geo-Z4 (Zone 4) n – negl N/A We found no evidence of its presence in this zone. Geo-Z5 (Zone 5) n – mod N/A We found no evidence of its presence in this zone. Geo-Z6 (Zone 6) n – high N/A 2 points in France; this is not enough evidence for a “yes” answer. Geo-Z7 (Zone 7) y - low N/A A few points in Spain and France, 2 in Italy Geo-Z8 (Zone 8) y – negl N/A Many points in Spain and France, 3 in Corsica, 1 in Sicily Geo-Z9 (Zone 9) y – negl N/A Many points in Spain and France; some in Italy, Algeria, and Australia; 7 in Corsica; 5 in New Zealand; 3 in Sicily, Sardinia, and Crete; 2 in Portugal; 1 in Croatia, Tunisia, and Morocco Geo-Z10 (Zone 10) y - negl N/A Many points in Spain and France, a few in Corsica, 7 in Algeria, 6 in Crete, 4 in Italy and Australia, 3 in Sicily, 2 in Sardinia and Greece, 1 in New Zealand Geo-Z11 (Zone 11) y - negl N/A Many points in Spain, 5 in Crete and Australia, 4 in Greece, 3 in Sardinia, 1 in Sicily and Corsica

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Question ID Answer - Score Notes (and references) Uncertainty Geo-Z12 (Zone 12) n - high N/A We found no evidence of its presence in this zone. Geo-Z13 (Zone 13) n - low N/A We found no evidence of its presence in this zone. Köppen -Geiger climate classes Geo-C1 (Tropical rainforest) n - negl N/A We found no evidence of its presence in this climate class. Geo-C2 (Tropical savanna) n - negl N/A We found no evidence of presence in this climate class. Geo-C3 (Steppe) y - negl N/A Many points in Spain, 4 in Australia, 1 in Algeria Geo-C4 (Desert) n - high N/A We found no evidence of presence in this climate class, but we have high uncertainty because it does grow in warm climates with little precipitation. Geo-C5 (Mediterranean) y - negl N/A Many points in Algeria, France, and Spain; some in Crete, Corsica, and Italy; a few in Sicily; 6 in Greece; 5 in Sardinia; 2 in Portugal; 1 in Morocco and Tunisia Geo-C6 (Humid subtropical) y - low N/A 9 points in Spain, 6 in France, 2 in Italy, 1 in Croatia Geo-C7 (Marine west coast) y - negl N/A Many points in Australia, France, and Spain; 4 in New Zealand Geo-C8 (Humid cont. warm sum.) n - high N/A We found no evidence of presence in this climate class; however, we answered "no" with high uncertainty because this climate is intermediate between others for which we did find evidence. Geo-C9 (Humid cont. cool sum.) n - high N/A 1 point in France and Spain. This is not enough evidence for a “yes” answer. Geo-C10 (Subarctic) n - high N/A 1 point in Spain. This is not enough evidence for a “yes” answer. Geo-C11 (Tundra) n - negl N/A We found no evidence of its presence in this climate class. Geo-C12 (Icecap) n - negl N/A We found no evidence of its presence in this climate class. 10-inch precipitation bands Geo-R1 (0-10 inches; 0-25 cm) y - negl N/A Many points in Spain, 3 in Crete Geo-R2 (10-20 inches; 25-51 cm) y - negl N/A Many points in Spain and France; a few in Crete; 5 in Sicily; 4 in Italy, Corsica, and Greece; 2 in Sardinia and Algeria Geo-R3 (20-30 inches; 51-76 cm) y - negl N/A Many points in Spain, France, and Australia; some in Italy; 6 in Sardinia and Algeria; 4 in Sicily, Corsica, and Greece; 2 in Portugal; 1 in Tunisia Geo-R4 (30-40 inches; 76-102 cm) y - negl N/A Many points in Spain, some in France and Algeria, 9 in Corsica, 5 in New Zealand, 2 in Australia, 1 in Italy and Morocco Geo-R5 (40-50 inches; 102-127 cm) y - negl N/A A few points in France; 9 in Corsica; 5 in Australia; 1 in Croatia, Greece, and New Zealand

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Question ID Answer - Score Notes (and references) Uncertainty Geo-R6 (50-60 inches; 127-152 cm) n - high N/A 2 points in Italy; this is not enough evidence for a “yes” answer. Geo-R7 (60-70 inches; 152-178 cm) n - mod N/A We found no evidence of its presence in this precipitation band. Geo-R8 (70-80 inches; 178-203 cm) n - negl N/A We found no evidence of its presence in this precipitation band. Geo-R9 (80-90 inches; 203-229 cm) n - negl N/A We found no evidence of its presence in this precipitation band. Geo-R10 (90-100 inches; 229-254 cm) n - negl N/A We found no evidence of its presence in this precipitation band. Geo-R11 (100+ inches; 254+ cm) n - negl N/A We found no evidence of its presence in this precipitation band. ENTRY POTENTIAL Ent-1 (Plant already here) n - mod 0 Calicotome spinosa was previously detected in California (Oki, 2016), but the plants have been removed (Kelch, 2020). The seed bank, however, has not been assessed (Kelch, 2020). Ent-2 (Plant proposed for entry, or entry n - low 0 We found no evidence that this species is is imminent ) proposed for importation. Ent-3 [Human value & cultivation/trade b - high 0.05 We found no evidence of current commercial status: (a) Neither cultivated or positively sale of C. spinosa (Amazon, 2020; Plant valued; (b) Not cultivated, but positively Information Online, 2020) and minimal valued or potentially beneficial; (c) discussion of it on gardening forums (Dave's Cultivated, but no evidence of trade or Garden, 2020; GardenWeb, 2020). It is, resale; (d) Commercially cultivated or however, recommended for xeriscaping other evidence of trade or resale] (Dave's Garden, 2020) and was introduced to Australia as an ornamental and hedge plant in the 1860s (Paynter et al., 2003a). We found no evidence that it is currently cultivated, but we did find evidence of it being valued; therefore, we answered "b" with high uncertainty. Ent-4 (Entry as a contaminant) Ent-4a (Plant present in Canada, n - low The plant is native to the Mediterranean Mexico, Central America, the Caribbean (NPGS, 2020) and naturalized in Australia or China ) and New Zealand (Biosecurity Queensland, 2016; Howell and Sawyer, 2006). We found no evidence of its presence anywhere else. Ent-4b (Contaminant of plant n - low 0 We found no evidence that C. spinosa is a propagative material (except seeds)) contaminant of propagative material. Ent-4c (Contaminant of seeds for y - low 0.04 It is listed as a regulated weed seed planting) contaminant of seed for sowing in New Zealand (MAF Biosecurity New Zealand, 2012). Ent-4d (Contaminant of ballast water) n - low 0 We found no evidence that C. spinosa is a contaminant of ballast. Ent-4e (Contaminant of aquarium n - negl 0 We found no evidence that C. spinosa is a plants or other aquarium products) contaminant of aquarium products. Furthermore, it is a terrestrial plant that grows in dry areas (Parsons and

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Question ID Answer - Score Notes (and references) Uncertainty Cuthbertson, 2001), so it is highly unlikely to be associated with aquariums. Ent-4f (Contaminant of landscape n - low 0 We found no evidence that C. spinosa is a products) contaminant of landscaping materials. Seeds can be dispersed in soil (Parsons and Cuthbertson, 2001), but this is in the context of earth-moving for road work, not trade of soil for landscaping. Ent-4g (Contaminant of containers, y - low 0.02 Seeds can be dispersed on machinery packing materials, trade goods, (Biosecurity Queensland, 2016). equipment or conveyances) Ent-4h (Contaminants of fruit, y - mod 0.01 Seeds can be contaminants of agricultural vegetables, or other products for products (Biosecurity Queensland, 2016), consumption or processing) including animal feed (Agriculture Victoria, 2020), and C. spinosa is listed as a regulated weed seed contaminant of grain and seed for consumption in New Zealand (MAF Biosecurity New Zealand, 2009). We found no records, however, of interception at U.S. ports of entry (AQAS, 2020). Ent-4i (Contaminant of some other a - low 0 We found no evidence that C. spinosa is pathway) likely to follow any pathway that is not already listed. Ent-5 (Likely to enter through natural n - negl 0 We found no evidence that C. spinosa is dispersal) present in Canada, Mexico, or the Caribbean (GBIF Secretariat, 2019; NPGS, 2020). Therefore, it is highly unlikely to disperse naturally into the United States.

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